Optical scanning apparatus

ABSTRACT

The optical scanning apparatus including a light source unit having plurality laser light sources for emitting laser light and one lens in which the laser light emitted from the plurality laser light sources is transmitted, a deflect device that deflects and scans the laser light on an image bearing member, an optical member that images the laser light on the image bearing member, a housing that internally includes the deflect device and the optical member, the housing forms an opening portion that passes through the laser light emitted from the plurality of the laser light sources, and an elastic member that blocks a gap between the lens and the opening portion, the elastic member being pinched between the lens and the housing. It achieves sealing of the flow-in path and sealing of the gap between the light source unit and the housing with a simple configuration.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.12/511,880, filed Jul. 29, 2009 (currently pending), which isincorporated by reference herein in its entirety, as if fully set forthherein, and claims the benefit of priority under 35 U.S.C. §119, basedon Japanese Priority Application No. 2008-205634, filed Aug. 8, 2008,which is incorporated by reference herein in its entirety, as if fullyset forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical scanning apparatus mountedon an image forming apparatus such as a laser beam printer or a digitalcopier including an electrophotographic process means.

2. Description of the Related Art

In recent years, improvement in dust proof performance of the opticalscanning apparatus is desired in accordance with increase in speed ofthe laser beam printer and diversification of the use environment.

As a conventional embodiment, an optical scanning apparatus described inJapanese Patent Application Laid-Open No. H11-242176 is illustrated inFIGS. 14 and 15.

As illustrated in FIG. 14, an optical scanning apparatus 140 emits laserlight 130 from a fitted and assembled light source device (light sourceunit) 106. The laser light 130 emitted from the light source device 106passes through a cylindrical lens 117 and provides a linear image on areflection surface of a polygon mirror 115. The laser light 130 isdeflected by rotating the polygon mirror 115, and is imaged and scannedon a surface to be scanned (e.g., photosensitive drum) (not shown)through a scanning lens 118 and a folding mirror 119, thereby forming anelectrostatic latent image.

The light source device 106 emits the laser light 130 from a laser lightsource (not shown) serving as a light source, and the laser light 130 isconverted to a parallel light flux by a collimator lens (not shown). Asillustrated in FIG. 15, the laser light source is fixed to a laserholder 102 by using a known technology such as press-fit, and thecollimator lens is fixed after being position adjusted with respect tothe laser holder 102. The focus and optical axis adjustment of the laserlight source and the collimator lens is thereby carried out.

When the polygon mirror 115 is rotated, the surrounding air is alsostirred, and the air enters and exits an optical box (housing) 107. Atthe same time, dust at the periphery of the optical box 107 is alsotaken in, and such dust adheres to the polygon mirror 115, the scanninglens 118, and the folding mirror 119. The degree of adhesion isaccelerated by the number of revolutions of the polygon mirror 115 andthe extent of pollution of the air of the use environment. As a result,there may arise a problem that unevenness of light intensity is caused.

The main flow-in path of the dust from the vicinity of the laser lightsource is the gap between the light source device 106 and the opticalbox 107. In Japanese Patent Application Laid-Open No. H11-242176, anelastic member 114 is sandwiched between the fitted light source device106 and the optical box 107 to prevent the dust from flowing into theinterior of the optical box 107 from the flow-in path.

However, the following problems and restrictions still exist in theconventional technology described above.

In Japanese Patent Application Laid-Open No. H11-242176, the flow-inpath that passes through the light source device itself barely exists,and the desired dust proof performance is achieved by simply sandwichingthe elastic member between the light source device and the optical box.

However, such achievement is realized by adopting a system including alaser light source of a simple system, the system being configured suchthat the laser light source is press-fit to the laser holder, inJapanese Patent Application Laid-Open No. H11-242176. In other words,the press-fit region of the laser light source is in a substantiallysealed state. Further, although the collimator lens is bonded at aminimum extent of only three points on the periphery and there is a gapregion without adhesive on the periphery, a problem does not arisebecause this kind of the gap has an extremely small area.

Consideration of bonding the entire periphery of the collimator lens toenhance sealability is known. Such consideration can be made in the casewhere the collimator lens is sufficiently small, but is restricted ifthe collimator lens is a large lens such as a compound collimator lensin which collimator lenses of multiple systems are integrated.

When adopting the compound collimator lens, the laser light source sideneeds to be adjusted and bonded for adjusting the positions of thecollimator lens of each system and the laser light source.

Therefore, in the configuration adopting the compound collimator lens,the flow-in path of dust that passes through the light source deviceitself exists, and improvement is desired from the standpoint of dustproof performance.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above. An object ofthe present invention is therefore to provide an optical scanningapparatus for sealing the flow-in path that passes through the lightsource unit itself and sealing the gap between the light source unit andthe housing with a simple configuration in a configuration using acompound incoming lens.

Another object of the present invention is to provide an n opticalscanning apparatus including a light source unit including a pluralityof laser light sources for emitting laser light and one lens in whichthe laser light emitted from the plurality of the laser light sources istransmitted, the one lens being provided with respect to the pluralityof the laser light sources, a deflect device that deflects and scans thelaser light on an image bearing member, an optical member that imagesthe laser light on the image bearing member, a housing that internallyincludes the deflect device and the optical member, wherein in acondition where the light source unit is assembled to the housing, thehousing forms an opening portion that passes through the laser lightemitted from the plurality of the laser light sources, and an elasticmember that blocks a gap between the lens and the opening portion of thehousing, the elastic member being pinched between the lens and thehousing.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments and accompanied drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a cross-sectional view of an optical scanning apparatus of afirst embodiment taken in a main scanning direction.

FIG. 1B is a schematic perspective view of the optical scanningapparatus of the first embodiment seen from a rear surface side of alaser light source.

FIG. 2 is a schematic perspective view of the optical scanning apparatusof the first embodiment.

FIG. 3 is a schematic perspective view of a light source device of thefirst embodiment.

FIG. 4 is a cross-sectional view of the light source device of the firstembodiment taken in a sub-scanning direction.

FIG. 5 is a view illustrating an assembly adjustment method for thelight source device of the first embodiment.

FIG. 6 is a schematic cross-sectional view illustrating a flow-in pathof dust to an optical box when a dust proof seal is not present in thefirst embodiment.

FIG. 7 is a schematic view illustrating another mode of the firstembodiment.

FIG. 8 is a schematic perspective view of a light source device of asecond embodiment.

FIG. 9 is a cross-sectional view of an optical scanning apparatus of thesecond embodiment taken in a main scanning direction.

FIG. 10 is a schematic view illustrating another mode of the secondembodiment.

FIG. 11 is a schematic perspective view of a light source device of athird embodiment.

FIG. 12 is a cross-sectional view of an optical scanning apparatus ofthe third embodiment taken in a main scanning direction.

FIG. 13 is a schematic view illustrating another mode of the thirdembodiment.

FIG. 14 is an explanatory view of a conventional optical scanningapparatus.

FIG. 15 is an explanatory view of a conventional light source device.

FIG. 16 is a schematic perspective view of a light source deviceproposed by the applicant of the present invention.

FIG. 17 is a schematic view of the light source device of FIG. 16 seenfrom the laser light source side.

FIG. 18 is an explanatory view of a bonding region of the light sourcedevice of FIG. 16.

DESCRIPTION OF THE EMBODIMENTS

First, the exemplary embodiments proposed by the applicant of thepresent invention for the system including the laser light source ofmultiple systems, the system being such that the laser light sources areadjusted and bonded, are described with reference to FIGS. 16 to 18.

FIG. 16 is a schematic perspective view of a light source device 231,FIG. 17 is a schematic view of the light source device 231 seen from alaser light source side, and FIG. 18 is a view describing a bondingregion of the light source device 231 and illustrates an enlarged viewof the vicinity of a laser light source 201 u.

The light source device 231 adopts a system including laser lightsources 201 u, 201 d as two systems, where one incoming lens 202transmits the laser light of the two systems.

Thus, as opposed to the conventional device of FIG. 14, the incominglens 202 is first fixed to a lens support member 206 through a knowntechnology such as bonding in the assembly of the light source device231. The two laser light sources 201 u, 201 d are fixed after beingindividually position adjusted with respect to the incoming lens 202 byway of laser support members 205 u, 205 d fixed through the technologysuch as press-fit. The focus and optical axis of the laser light sources201 u, 201 d and the incoming lens 202 are adjusted in such manner.

Note that the important characteristics here lies in the manner ofapplying the adhesive in the bonding of the incoming lens 202 and thebonding of the laser light sources 201 u, 201 d.

Stable assembly at high accuracy that does not tolerate even a slightposition shift is desired on the optical components such as the incominglens and the laser light source. Since assembly in a short period oftime is desired in a tact system, ultraviolet curing type that rapidlycures with generation of heat is used for such optical components.Therefore, the adhesive is usually applied with proper balance atminimum amount only at three points at the periphery of the component asin FIG. 18.

Since the incoming lens transmits the laser light of multiple systemsand thus becomes large, adverse effect may increase if the entireperiphery is bonded. The bonding region of the laser light source isalso a minimum of only three points at the periphery, and two gapregions without the adhesive still exist on the periphery.

In other words, in the light source device as illustrated in FIGS. 16 to18, the flow-in path that passes through the light source device itselfinevitably remains, and improvement is desired from the standpoint ofdust proof performance.

The inventors contrived the present invention after thorough review toenhance the dust proof performance in the optical scanning apparatus ofa system including laser light sources of multiple systems, the systembeing such that the laser light sources are adjusted and bonded.

An exemplary embodiment for implementing the present invention isillustratively described in detail below with reference to the drawings.The dimension, material, shape and relative arrangement of thecomponents described in the exemplary embodiment are to be appropriatelychanged according to the configuration and various conditions of theapparatus to which the present invention is applied, and are not to beconsidered as limiting the scope of the invention by the followingembodiments.

A first embodiment of the present invention is described below. Anoptical scanning apparatus of this embodiment is an optical scanningapparatus appropriate for a tandem-type color image forming device forforming a color image on a photosensitive member serving as an imagebearing member for four colors of Y (Yellow), M (Magenta), C (Cyan), andBK (Black).

FIG. 2 is a schematic perspective view of the optical scanning apparatusof this embodiment. In the optical components illustrated in FIG. 2, ifsimilar components are used on the left and the right with a polygonmirror 73 being interposed therebetween, the left and right aredistinguished by appending a and b after the common number. In thefollowing description, a and b are appended after the number only whenleft and right need to be distinguished.

The optical scanning apparatus 50 illustrated in FIG. 2 is provided with(internally includes) a polygon mirror 73, scanning lenses 75 a, 75 b,76 a, 76 b, 77 a and 77 b and folding mirrors 78 a, 78 b, 79 a, 79 b, 80a, 80 b 81 a and 81 b in one optical box (optical frame body) 90. Theoptical box 90 is attached with light source devices 31 a, 31 b servingas light source units. The light source devices 31 a, 31 b (hereinaftertotally referred to as 31 in the specification) include semiconductorlasers 1Y, 1M, 1C, 1Bk serving as laser light sources that emit laserlight modulated for each color of Y (Yellow), M (Magenta), C (Cyan), andBk (Black). The semiconductor lasers 1Y, 1M, 1C, 1Bk are connected tocircuit substrates 82 a, 82 b. The optical box 90 corresponds to ahousing. The polygon mirror 73 corresponds to a deflect device fordeflecting and scanning the laser light on the image bearing member. Thescanning lenses 75 a, 75 b, 76 a, 76 b, 77 a and 77 b and the foldingmirrors 78 a, 78 b, 79 a, 79 b, 80 a, 80 b, 81 a and 81 b correspond tothe optical members for imaging the laser light on the image bearingmember.

The semiconductor lasers 1Y, 1M, 1C, and 1Bk are arranged by twos aboveand below (sub-scanning direction) in each of the light source devices31 a, 31 b(31), to be described later. The laser light emitted from thesemiconductor lasers 1Y, 1M, 1C, 1Bk transmits through an anamorphiclens 2 (see FIG. 1) serving as a lens, and then linearly images on twodifferent reflection surfaces 73 a, 73 b of the polygon mirror 73 thatrotates at high speed.

The polygon mirror 73 rotates at high speed by a drive motor 74. Thelaser light deflected and scanned by the polygon mirror 73 is guided toand scanned on a corresponding photosensitive member (not shown) by theplural scanning lenses 75 a, 75 b, 76 a, 76 b, 77 a and 77 b and thefolding mirrors 78 a, 78 b, 79 a, 79 b, 80 a, 80 b, 81 a and 82 barranged symmetric to the rotation axis of the polygon mirror 73.

FIG. 3 is a schematic perspective view illustrating the light sourcedevice 31 and FIG. 4 is a schematic cross-sectional view in thesub-scanning direction illustrating the light source device 31.

As illustrated in the drawings, the light source device 31 includeslaser light sources 1 u (correspond to one of semiconductor laser 1M andsemiconductor laser 1Bk), 1 d (correspond to one of semiconductor laser1Y and semiconductor laser 1C), and the compound anamorphic lens 2,which is the imaging lens. The anamorphic lens 2 has a lens unit havingdifferent power in the main scanning direction and the sub-scanningdirection arranged at two locations above and below in correspondence tothe two laser light sources. In other words, one anamorphic lens 2 isarranged with respect to the plurality of the laser light sources.

The main scanning direction is the direction parallel to the directionof scanning the laser light deflected by the polygon mirror 73 on thephotosensitive member, and the sub-scanning direction is the directionparallel to the rotation axis of the polygon mirror 73. In thisembodiment, for the sake of convenience of the explanation, the verticaldirection is the vertical direction when the bottom surface of theoptical box 90 in which the polygon mirror 73 and the optical componentsare arranged as illustrated in FIG. 2 is horizontal, and the verticaldirection in this case is the sub-scanning direction.

In this embodiment, the anamorphic lens 2 is arranged for the lens, butthis is not the sole case. That is, the lens is not limited to theanamorphic lens as long as a function of aligning the shape of the laserbeam is provided for the incoming lens. It suffices that the lens canobtain effects same as when the anamorphic lens 2 is applied merely.

The laser light sources 1 u, 1 d are fixed to the laser support members5 u, 5 d through an existing technology such as press-fit. Theanamorphic lens 2 is fixed to a bonding portion 9 of the lens supportmember 6 through an existing technology such as bonding. The lasersupport members 5 u, 5 d are position adjusted at high accuracy withrespect to the anamorphic lens 2, and then bonded and fixed to the lenssupport member 6 with light curing adhesive (not shown). The lenssupport member 6 is arranged at the periphery of the anamorphic lens 2,and includes a protruding portion 8 projecting to the downstream side inthe laser light emitting direction (downstream side in the optical pathof the laser light) with respect to the lens emitting surface 2 a or thesurface on the laser light emitting side of the anamorphic lens 2.

According to such configuration, the laser light fluxes Lu, Ld areemitted in the light source device 31 as illustrated in FIG. 4. Thelaser light fluxes Lu, Ld, which are divergent light emitted from thelaser light sources 1 u, 1 d, pass through the anamorphic lens 2, andare converted to parallel light in the main scanning direction andconverted to converged light in the sub-scanning direction. The laserlight flux Lu emitted from the laser light source 1 u and the laserlight flux Ld emitted from the laser light source 1 d are arranged so asto form a predetermined angle □ with respect to each other aftertransmitting through the anamorphic lens 2. Thus, the laser light fluxesenter their positions proximate to each other on the reflection surfaceof the polygon mirror 73 illustrated in FIG. 2.

FIG. 5 is an enlarged view of the vicinity of the laser light source inthe position adjustment of the laser support member 5 u using a jig, andillustrates the assembly adjustment method for the light source deviceof this embodiment. As illustrated in FIG. 5, the laser support member 5u into which the laser light sources 1 u is fixed is gripped by chucks51, 52.

As illustrated in FIG. 5, the laser support member 5 u is clamped withthe chucks 51, 52 and position adjusted in three directions of X, Y, Z.Thus, an adjustment clearance as illustrated with a hatched portion 10is necessary between the laser support member 5 u and the lens supportmember 6 such that the laser support member 5 u does not interfere withthe lens support member 6 even if moved in position adjustment.

As described above, in order to bond and fix at high accuracy in a shortperiod of time, a minimum amount of adhesive is suitably applied to thebalanced region, and thus the adjustment clearance remains as it is andthe flow-in path that passes through the light source device remains asillustrated in FIG. 4.

The dust proof mode, which is a characteristic of this embodiment, isdescribed with reference to FIGS. 1 and 6. The characteristic of thisembodiment lies in inexpensively and easily preventing the flow-in ofdust from the vicinity of the laser light source without degrading theoptical performance.

FIG. 1A is a schematic cross-sectional view of the optical scanningapparatus of this embodiment taken in the main scanning direction, andFIG. 1B is a schematic perspective view of the optical scanningapparatus of this embodiment seen from the rear surface side of thelaser light source (upstream side in laser light emitting direction).FIG. 6 is a schematic cross-sectional view taken in the main scanningdirection illustrating the flow-in path of dust to the optical box 90when a dust proof seal 7 serving as an elastic member used in thisembodiment is not present.

As illustrated in FIG. 6, when the dust proof seal 7 is not used, theflow-in path of dust from the vicinity of the light source device 31 tothe optical box 90 includes a path P1 from the gap between the lightsource device 31 and the optical box 90, and a path P2 passing throughthe light source device 31. If any one of the paths is present, suchpath acts as the flow-in path of the dust, whereby the dust flows intothe optical box 90 from an opening portion 90 a formed in the opticalbox 90 to pass the laser light, and the optical performance may degrade.

In order to prevent degradation of the optical performance caused bydust, the dust from the two flow-in paths needs to be shielded. Asdescribed in Japanese Patent Application Laid-Open No. H11-242176, amethod of shielding the gap of the light source device 31 and theoptical box 90 by the elastic member is effective.

A method of contacting the anamorphic lens 2 and the lens support member6 over the entire surface and shielding the flow-in path is alsoconsidered to prevent the dust from flowing-in from the path that passesthrough the light source device 31. However, a very high positionaccuracy is demanded on the anamorphic lens 2, and it is difficult toguarantee high accuracy over the entire contacting surface with respectto the lens support member 6 generally made through resin molding. Amethod of bonding with the lens support member 6 over the entireemitting surface of the anamorphic lens 2 and shielding the flow-in pathis also considered, but is not suitable because the fluctuation due tovariation in curing of the adhesive and fluctuation due to expansion andcontraction of adhesive under various environments have a highpossibility of occurring.

In this embodiment, the dust proof seal 7 serving as the elastic memberis used for the method of shielding the flow-in path from the path thatpasses through the light source device 31.

The elastic member is made of material such as rubber form orpolyurethane foam, and excels in sealability of the gap because it haslow hardness and easily follows the shape of the counterpart, where thereaction force when squashed is minor because the elastic member deformswith low load. Thus, the elastic member is suited for providing at theperiphery of the anamorphic lens 2 where high position accuracy isdemanded, as described above.

As illustrated in FIG. 1B, the dust proof seal 7 serving as the elasticmember is squashed to the desired thickness by being sandwiched betweenthe optical box 90 and anamorphic lens 2 in each of the light sourcedevices 31 a, 31 b. In assembling, assembly is realized withsatisfactory workability by adopting the method of fitting the dustproof seal 7 into the optical box 90, and thereafter assembling thelight source device 31.

The dust proof seal 7 is arranged to contact the surface (lens emittingsurface) 2 a on the laser light emitting side of the anamorphic lens 2and the reception surface 60 of the optical box 90 faced thereto so asto be sandwiched between the optical box 90 and the light source device31. The reception surface 60 corresponds to a first opposing surface.

According to such configuration, as illustrated in FIG. 1A which is thecross-sectional view in the main scanning direction of the opticalscanning apparatus, both the path P1 from the gap between the lightsource device 31 and the optical box 90 and the path P2 that passesthrough the light source device can be shielded with one elastic member(dust proof seal 7). Therefore, the gap between the anamorphic lens 2and the opening portion 90 a of the optical box 90 can be blocked, andthe dust is prevented from flowing-in from the vicinity of the laserlight source to the interior of the optical box 90.

The protruding portion 8 of the lens support member 6 projects out withrespect to the lens emitting surface 2 a of the anamorphic lens 2, andthus the dust proof seal 7 is pinched between the lens emitting surface2 a and the reception surface 60 and pinched between the protrudingportion 8 and the reception surface 60. Thus, if the protruding portion8 of the lens support member 6 projects out with respect to the lensemitting surface 2 a of the anamorphic lens 2, the dust proof seal 7 issquashed more between the protruding portion 8 and the reception surface60 than between the anamorphic lens 2 and the reception surface 60.

Therefore, the reaction force received by squashing the dust proof seal7 applies more on the lens support member 6 including the protrudingportion 8 than on the anamorphic lens 2. The reaction force generated bycontacting the dust proof seal 7 to the reception surface 60 thus can bereceived by the protruding portion 8, and the reaction force on theanamorphic lens 2 can be suppressed to a minimum. In other words, theanamorphic lens 2 is less susceptible to the reaction force generated bycontacting the dust proof seal 7 to the reception surface 60 in thisembodiment. As described above, the load on the anamorphic lens 2 needsto be suppressed as much as possible because very high position accuracyis demanded on the anamorphic lens 2.

According to such configuration, the dust is prevented from flowing-infrom the vicinity of the laser light source at lower cost withoutaffecting the optical performance.

According to this embodiment, therefore, the dust proof seal 7 isprovided so as to be sandwiched between the anamorphic lens 2 and theoptical box 90 in the system including the laser light sources of twosystems, the system being set such that the laser light sources areadjusted and bonded. Thus, the gap passing through the light sourcedevice can be blocked while blocking the gap between the light sourcedevice 31 and the optical box 90, and in addition, the dust can beprevented with one elastic member.

Thus, the dust proof performance equal to or higher than that in thesystem including the laser light source of one system or that in thesystem in which the laser is press fit of the related art can beinexpensively and easily achieved in the system including the laserlight sources of two systems, the system being set such that the laserlight sources are adjusted and bonded. Thus, the image qualitydegradation arising from the stain by the dust can be more effectivelyprevented particularly in the optical scanning apparatus for the colorimage forming device.

In this embodiment, while the protruding portion 8 is provided over theentire periphery of the anamorphic lens 2, this should not be construedrestrictively. The reaction force generated by squashing the dust proofseal 7 merely needs to be received by the protruding portion than by theanamorphic lens 2, and thus the protruding portion does not need to beprovided over the entire periphery of the anamorphic lens 2. Forinstance, plural protruding portions projecting out with respect to theemitting surface side of the anamorphic lens 2 may be provided at theperiphery of the anamorphic lens 2, and plural protruding portions 11projecting out with respect to the emitting surface side of theanamorphic lens 2 may be configured as illustrated in FIG. 7.

A second embodiment of the present invention is described below.

In this embodiment, other types of the dust proof seal 7, the lenssupport member 6, the optical box 90, the opening portion 90 a, thereception surface 60, and the light source device 31 of the firstembodiment are illustrated. Description is made below using a dust proofseal 17, a lens support member 16, an optical box 91, an opening portion91 a, a reception surface 61, and a light source device 32. In thisembodiment, the configuring portions different from those in the firstembodiment are described, and the description on the configuringportions similar to the first embodiment is omitted.

FIG. 8 is a schematic perspective view of the light source device 32 ofthis embodiment, and FIG. 9 is a schematic cross-sectional view in themain scanning direction of the optical scanning apparatus.

In this embodiment, the dust proof seal 17 is pinched (contacted) by theentire periphery (entire surface perpendicular to lens emitting surface2 a) of the lens side surface 2 b, which is a surface parallel to thelaser light emitting direction in the anamorphic lens 2, and thereception surface 61 of the optical box 91 faced thereto. Thus, the twoflow-in paths P1, P2 are shielded as illustrated in FIG. 9. Thereception surface 61 corresponds to a second opposing surface.

The concern that arises in this case is that the dust proof seal 17 maytwist in assembling and may not be securely contacted with the receptionsurface 61, thereby forming the flow-in path of the dust. Thus, in thisconfiguration, the reception surface 61 on the optical box 91 side has atapered shape that gradually narrows towards the emitting direction ofthe laser beam.

The reception surface 61 merely needs to have a configuration in whichthe width in at least one direction of the directions orthogonal to thelaser light emitting direction gradually narrows towards the downstreamside in the laser light emitting direction. A case where thecross-sectional shape of the inner wall of the reception surface 61 isformed to a substantially square shape so as to correspond to the dustproof seal 17 having an outer shape of a substantially square shapeillustrated in FIG. 8 is as described below. The width between at leastone of the pairs of inner walls of the two pairs of opposing inner wallsconfiguring the square cross-section merely needs to gradually narrowtowards the downstream side in the laser light emitting direction.

According to such configuration, in assembling, the dust proof seal 17is first fitted to the light source device 32 as illustrated in FIG. 8,and then the light source device 32 is assembled to the optical box 91.The dust proof seal 17 thus changes shape in conformity with the taperedshape of the reception surface 61, whereby irregular deformation such astwisting is less likely to occur.

The direction the reaction force generated by squashing the dust proofseal 17 acts is the main scanning direction and the sub-scanningdirection. The position accuracy in the main scanning direction and thesub-scanning direction demanded on the anamorphic lens 2 is low incomparison with the optical axis direction, and thus the degradation inthe optical performance caused by squashing the dust proof seal 17 canbe avoided.

In this embodiment, while the dust proof seal 17 and the optical box 91are contacted in the main scanning direction and the sub-scanningdirection, this should not be construed restrictively. In another mode,as illustrated in FIG. 10, even if a dust proof seal 18 is configured tocontact the optical box 91 in the optical axis direction, the dust proofseal 18 can be contacted in the main scanning direction and thesub-scanning direction with respect to the optical box 91 due to itselasticity, and effects similar to the above can be obtained.

The third embodiment of the present invention is described below.

In this embodiment, other types of the dust proof seal 17, the lenssupport member 16, and the light source device 32 of the secondembodiment are illustrated. Description is made below using a dust proofseal 27, a lens support member 26, and a light source device 33. In thisembodiment, the configuring portions different from those of the firstand second embodiments are described, and the description on theconfiguring portions similar to the first and second embodiments isomitted.

FIG. 11 is a schematic perspective view of the light source device 33 ofthis embodiment, and FIG. 12 is a schematic cross-sectional view in themain scanning direction of the optical scanning apparatus.

In this embodiment, the dust proof seal 27 is pinched (contacted) by alens incoming surface 2 c, which is the surface on the laser lightincoming side of the anamorphic lens 2, an opposing surface 26 a of alens support member 26 facing the lens incoming surface 2 c, and thereception surface 61 of the optical box 91 orthogonal to the lensincoming surface 2 c. Thus, two flow-in paths P1, P2 are shielded as inFIG. 12. The reception surface 61 is a surface parallel to the laserlight emitting direction, and corresponds to a fourth opposing surfaceof the optical box 91 provided so as to face the entire periphery of thelens side surface 2 b, which is the surface parallel to the laser lightemitting direction in the anamorphic lens 2. The opposing surface 26 acorresponds to the third opposing surface.

As in the case of the second embodiment, the concern that arises in thiscase is that the dust proof seal 27 may twist in assembling and may notbe securely contacted with the optical box 91, thereby forming theflow-in path of the dust. Thus, in this configuration, as in the case ofthe second embodiment, the reception surface 61 on the optical box 91side has a tapered shape that gradually narrows towards the emittingdirection of the laser light.

In assembling, the anamorphic lens 2 is bonded with the dust proof seal27 sandwiched between the anamorphic lens 2 and the lens support member26, and the laser support member 5 is adjusted in such state to preparethe light source device 33.

In the first and second embodiments, the reaction force generated bysquashing the dust proof seal is received in a state of the light sourcedevice, in which the position adjustment of the anamorphic lens and thelaser light source is completed.

In this configuration, on the other hand, the laser light sources 1 u, 1d are adjusted and the light source device 33 is formed with theanamorphic lens 2 already receiving the reaction force generated bysquashing the dust proof seal 27.

Thus, if after the light source device 33 is formed, the load newlyapplies on the anamorphic lens 2 does not exist, and thus thedegradation of the optical performance can be prevented.

In this embodiment, while the dust proof seal 27 and the optical box 91are contacted in the main scanning direction and the sub-scanningdirection, this should not be construed restrictively. In another mode,as illustrated in FIG. 13, even if a dust proof seal 28 is configured tocontact the optical box 91 in the optical axis direction, the dust proofseal 28 can be contacted in the main scanning direction and thesub-scanning direction with respect to the optical box 91 due to itselasticity, and effects similar to the above can be obtained.

Therefore, according to the present invention, the flow-in path thatpasses through the light source unit itself can be sealed and the gapbetween the light source unit and the housing can also be sealed with asimple configuration in the configuration using the compound incominglens.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2008-205634, filed Aug. 8, 2008, which is hereby incorporated byreference herein in its entirety.

1-8. (canceled)
 9. An optical scanning apparatus comprising: a light source that emits a laser light; a lens through which the laser light emitted from the light source is passed; a support member supporting the lens; and a deflect device that deflects the laser light and scans an image bearing member with the laser light, wherein the support member includes a protruding portion projecting to the downstream side in a laser light emitting direction with respect to a laser light emitting surface of the lens, wherein in the laser emitting direction, the protruding portion surrounds a peripheral portion of the lens, wherein a plurality of plane surface portions are provided on outer surfaces of the protruding portion, and wherein in the laser emitting direction, an area surrounded by a plurality of planes each of which includes at least one plane surface portion among the plurality of the plane surface portions is a quadrilateral, and the area includes a whole of the lens therein.
 10. An optical scanning apparatus according to claim 9, wherein the plurality of the planes includes two planes extending in a main scanning direction of the lens, and wherein the lens is positioned between the two planes.
 11. An optical scanning apparatus according to claim 10, wherein the protruding portion includes an opened portion that exposes a side surface of the lens in the sub-scanning direction of the lens.
 12. An optical scanning apparatus according to claim 9, wherein the protruding portion includes four corner portions at each of which two of the plurality of the plane surface portions cross with each other.
 13. An optical scanning apparatus according to claim 9, wherein a gap is formed between the protruding portion and the peripheral portion of the lens in a direction perpendicular to the laser emitting direction.
 14. An optical scanning apparatus according to claim 9, wherein the support member supports the light source.
 15. An optical scanning apparatus according to claim 14, further comprising a housing that supports the support member and the deflect device.
 16. An optical scanning apparatus according to claim 9, wherein a laser light passing through the lens comes into the deflect device.
 17. An optical scanning apparatus according to claim 9, wherein the support member includes a bonding portion that adheres the support member with the lens, and wherein the bonding portion is provided to at a position opposite a laser light incident surface.
 18. An optical scanning apparatus according to claim 17, wherein the laser light incident surface of the lens abuts the bonding portion.
 19. An optical scanning apparatus comprising: a light source that emits a laser light; a lens through which the laser light emitted from the light source is passed; a support member supporting the lens; and a deflect device that deflects the laser light and scans an image bearing member with the laser light, wherein the support member includes a protruding portion projecting to the downstream side in a laser light emitting direction with respect to a laser light emitting surface of the lens, wherein in the laser emitting direction, the protruding portion surrounds a whole of the lens, wherein in the laser emitting direction, an area surrounded by the protruding portion is a quadrilateral.
 20. An optical scanning apparatus according to claim 19, wherein the protruding portion includes four corner portions, the four corner portions correspond to portions at each of which two of four side surfaces of a quadrangular prism crosses with each other, and the four side surfaces of the quadrangular prism surround the whole of the lens.
 21. An optical scanning apparatus according to claim 20, wherein the protruding portion includes four side surface portions corresponding to at least a part of each of the four side surfaces of the quadrangular prism.
 22. An optical scanning apparatus according to claim 21, wherein two side surfaces among the four side surfaces of the quadrangular prism extend in a main scanning direction of the lens, and wherein the two side surfaces oppose each other at both sides of the lens.
 23. An optical scanning apparatus according to claim 22, wherein the protruding portion includes an opened portion that exposes a side surface of the lens in a sub-scanning direction of the lens.
 24. An optical scanning apparatus according to claim 19, wherein a gap is formed between the protruding portion and the peripheral portion of the lens in a direction perpendicular to the laser emitting direction.
 25. An optical scanning apparatus according to claim 19, wherein the support member supports the light source.
 26. An optical scanning apparatus according to claim 25 further comprising a housing that supports the support member and the deflect device.
 27. An optical scanning apparatus according to claim 19, wherein a laser light passing through the lens comes into the deflect device.
 28. An optical scanning apparatus according to claim 19, wherein the support member includes a bonding portion on which the lens is adhered, and wherein the bonding portion is provided to oppose a laser light incident surface.
 29. An optical scanning apparatus according to claim 28, wherein the laser light incident surface of the lens abuts the bonding portion.
 30. An optical scanning apparatus comprising: a light source that emits a laser light; a lens through which the laser light emitted from the light source is passed; a support member supporting the lens; and a deflect device that deflects the laser light and scans an image bearing member with the laser light, wherein the support member includes a protruding portion projecting to the downstream side in a laser light emitting direction with respect to a laser light emitting surface of the lens, wherein the support member including a bonding portion on which the lens is adhered, and wherein the bonding portion is provided at a position opposite to a laser light incident surface of the lens.
 31. An optical scanning apparatus according to claim 30, wherein the laser light incident surface of the lens abuts the bonding portion.
 32. An optical scanning apparatus according to claim 31, wherein the lens has a function of aligning a shape of the laser beam.
 33. An optical scanning apparatus according to claim 30, wherein the lens is an anamorphic lens.
 34. An optical scanning apparatus according to claim 30, wherein the support member supports the light source.
 35. An optical scanning apparatus according to claim 34 further comprising a housing that supports the support member and the deflect device.
 36. An optical scanning apparatus according to claim 30, wherein a laser light passing through the lens comes into the deflect device. 